


throw you to the side

by steelrunner



Category: Voltron: Legendary Defender
Genre: Alpha Kuro, Alpha Shiro (Voltron), Alpha/Beta/Omega Dynamics, Alternate Universe - Modern Setting, Begging, Biting, Dirty Talk, F/F, Gender or Sex Swap, Girl Penis, Manhandling, Mating Cycles/In Heat, Non-Consensual Voyeurism, Omega Keith (Voltron), Penis In Vagina Sex, Possessive Behavior, Pseudo-Incest, Rough Sex, Sexting, Step-Sibling Incest
Language: English
Status: Completed
Published: 2020-12-21
Updated: 2020-12-21
Packaged: 2021-03-11 04:20:03
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 1,980
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/28219104
Author URL: https://archiveofourown.org/users/steelrunner/pseuds/steelrunner
Summary: It’s like someone is in the control room for Kira's brain and keeps pressing the large red button labeledhorny omega stereotype mode.
Relationships: Keith/Kuro (Voltron), Keith/Shiro (Voltron)
Comments: 3
Kudos: 60





	throw you to the side

**Author's Note:**

> More detailed warnings are located at the end of the fic.

Kira’s dad had gotten remarried when she was thirteen. Their new family included Kira’s stepmom - a beta to match Kira’s dad, and nice enough as people went - and two older stepsisters: twin girls, both alphas, and both with nicknames they preferred over their given ones. When Kira had first met Shiro, she had treated Kira with genuine friendliness, asking about Kira’s ambitions to go to flight school. Kuro had told her she would shove Kira’s head down a toilet if she caught her snooping in their stuff.

And here they are, six years later, and Kira is lying naked on Kuro’s bed, squirming anxiously as another wave of pre-heat sweeps over her.

Clarification: naked and _alone_. Kira rolls over on her side and grabs her phone, opening her messages.

_Kira: What the hell is taking you so long_

_Kuro: awww, someone’s getting desperate_

_can’t wait to get yourself knotted, huh?_

_Kira: Fuck you_

_Kuro: how wet are you?_

Kira squeezes her thighs together, shivering.

_Kira: pretty wet_

_Kuro: show me_

Kira lets her legs fall apart, thighs pale against the dark purple of Kuro’s duvet. Shiro and Kuro’s teenage bedroom is half-shadowed, half-lit by the setting sun coming through the blinds. One side is still neatly kept and covered in aerospace posters - Shiro’s - and Kuro’s side has devolved into a mess ever since she came back for break two weeks ago. Her dad and Mio are away on a camping trip, Shiro is spending the weekend with her high school friends, and as soon as Kuro comes back from whatever stupid errand she’s running, she’s going to be up here with Kira: just the two of them, all night long. Kuro could fuck her on every surface in the _house_ if she wanted.

At the crux of Kira’s legs, strings of slick connect her inner thighs, dripping across the dark snarl of hair between her legs. She slides her hand down over her mound - the brush is enough to draw another pulse of wetness from her - and spreads her fingers apart, pushing back her folds and exposing her hole. She angles her phone downwards and takes a snapshot, sending it off without looking at it.

_Kuro: fuck_

_when i get back, i’m gonna stuff you so full of cum you’ll be dripping for weeks_

_how did you survive while I was at college?_

_Kira: Snuck into your room and humped your pillows every night_

_Kuro: you little slut_

_don’t worry, I’ll give you what you need_

Kira groans, slick sliding over her thighs as she squeezes her legs together. Kuro had _better._

Thinking when she’s in heat is hard. Every coherent thought she tries to string together to distract herself gets interrupted the moment she shifts her hips or lifts her legs or even breathes. It’s like someone is in the control room for her brain and keeps pressing the large red button labeled _horny omega stereotype mode_. She had used to hate that, until Kuro had come along and shown her the advantages. Inevitably, Kira can’t help but think about Kuro, which is what nearly all her fantasies turn to - except for sometimes, on the longest nights, when she fantasizes about a warm voice and strong arms and a cute, scarred nose pressing against her shoulder -

“Hello! Anybody home?”

Kira’s mental control room goes into full panic mode. She jolts so hard she almost falls off the bed, then jumps up anyway. She maybe yelps. Maybe. Almost certainly. She starts looking around the clothes she had thrown off. No, no, no - anyone, _anyone_ but Shiro.

“Kira? Is that you up there?”

Footsteps on the stairs, in the hallway, and Kira dives for her t-shirt, snatching it up in front of her just as Shiro opens the door.

Shiro’s curious smile vanishes as soon as she sees Kira. “Whoa!” She covers her eyes with one hand, a polite reflex. Kira’s face burns - especially when Shiro drops her hand a moment later, a confused expression on her face. “Sorry Kira, I…wait, why are you in our room? Where’s your…uh…”

“I-I thought you were spending the weekend with Veronica,” Kira manages, not sure what else to say. Nothing is getting her out of this mess.

Shiro steps into the room, closing the door most of the way behind her; she’s dressed for a casual hang-out in her V-neck, military jacket, and jeans. She’s always had a solid head of height on Kira, but it doesn’t take that or her comparative strength be intimidating: her aura of breached propriety does that well enough. Kira’s stomach sinks as Shiro looks around, noticing the rumpled blankets on Kuro’s empty bed, Keith’s lack of clothing, and - oh god - probably the tracks of lubricant on her thighs as well.

“Wait - you’re - is Kuro…?” Shiro blinks. “You and…and Kuro?” she says disbelievingly, like she doesn’t even understand what’s she’s saying. “You and _Kuro_?”

Keith doesn’t reply. That’s answer enough.

The sharp spike of angry concern that rolls off of Shiro is palpable, and before Kira knows it she strides across the room, seizing Kira by the shoulder with cold metal fingers. This close to her heat, even years of practiced rebellion can’t keep Kira from freezing up at an alpha’s touch. The t-shirt flutters to the ground.

“Kira,” Shiro says - demands, really. She only hesitates for a moment as her gaze flicks downwards, though she blushes faintly as her eyes jerk back up. “Are you okay? Are you safe?”

“I’m fine,” Kira snaps. “And I’m perfectly safe too! It’s not like _that_!”

“I have to check, because this is insane,” Shiro retorts. She runs her other hand through her close-cut white hair, a familiar look of stress on her face. It’s the one she always makes when Kira manages to get in another fight at school. “This is _insane_.”

“It’s fine,” Kira says. “It’s - we’ve been doing this for a while, it’s nothing serious.”

Shiro steps closer as her nostrils flare, and Kira realizes she must have scented the distinctive aura of pre-heat surrounding her. “You were going to spend _your heat_ with her?”

“S-so what,” Kira forces out, but god, she can barely even think with Shiro’s hand on her shoulder and Shiro’s face so close to hers and Shiro’s scent clouding every inhale: _alpha, alpha, alpha_. “What are you pissed about, it’s none of your business!”

Shiro splutters at that, which Kira gets some satisfaction from. “She’s my sister,” she says, “and you’re our _stepsister_ , and she’s - she’s- “

“What?”

“A bully!” Shiro bursts out, her voice gone incredulous and angry and - and jealous? “We’ve lived with her for years - she’s arrogant and selfish and bratty and one of the _biggest_ assholes I’ve ever known! And you’re just going to let her - while you’re _in heat_?”

Kira glares up at Shiro, her cheeks hot. She knows this feeling well: it’s the feeling she gets when she’s well and truly pushed her luck, and she’s just about ready to push it off a cliff. She plants her hand against Shiro’s chest and shoves, sending her stumbling back a few feet. To keep Shiro off balance, she advances, ignoring her nakedness in favor of keeping eye contact with Shiro. “Maybe,” she says, mouth dry, “I _like_ that she’s a bully.”

Shiro narrows her eyes. Kira’s clit is throbbing, her cunt dripping, and her every instinct is screaming for her to just bend over for her alpha and let her punish Kira with a hard, brutal fuck, just like a good omega should.

Somewhere nearby, a car door slams.

The moment shatters. Kira whirls around, cursing, and Shiro blanches like the goody two-shoes she is. Before she can act, Kira grabs her by the front of her shirt, using the advantage of surprise to propel her back against the side wall. With her other hand, she reaches behind Shiro and yanks open the closet door, shoving the taller girl back among the racks of clothing. “Hide!”

Shiro stares down at her, eyes wide. “But - “

“No buts,” Kira snaps, and slams the door shut just as Kuro’s footsteps come pounding up the stairs. Kira turns around just as the door flies open again. This time Kuro is standing there: the mirror image of Shiro, save for the black hair and leather jacket and wicked, wicked grin.

“Kuro - “ Kira barely has time to say before Kuro is on her, grabbing her by the waist and kissing her so hard and rough Kira’s mind goes utterly blank. She swings Kira up, off her feet, before dumping her down on the nearest bed - which, in this case, is _Shiro’s_ bed.

“Kuro!” Kira gasps again when they pull apart. Kuro crowds her down on the bed, grabbing Kira’s wrists and pinning them above her head. She writhes, trying to pull her hands free. “Wait, you jerk - “

“Not a chance,” Kuro growls playfully. She buries her face in Kira’s neck, nipping at it, and all the bones in Kira’s body melt, her body swimming in heat as she sinks into the bed. “No more waiting. If you’re going to be a tease, you deal with the consequences.”

“But this is Shiro’s - “

Kuro cuts off Kira with the simple act of flipping her over, shoving her face-first into the mattress and holding her there. Kira has never felt so small, so powerless, as when Kuro’s rough hands yank Kira’s hips into place and her booted feet kick her legs apart. She hates herself for loving it, and she hates herself especially for loving it when she knows Shiro is watching.

“You’re so cute when you’re this desperate,” Kuro murmurs. The rough fabric of her jeans rubs against Kira’s ass as she bends down over her, nuzzling at the nape of Kira’s neck through the fall of her short hair. Kira is so ready she’s practically shaking, and when Kuro sinks her teeth into Kira’s neck it cuts all her strings, sends her plummeting down into the full force of her heat. She doesn’t have the restraint anymore to hold back her brief cry or keep from pushing back as Kuro’s hips grind against hers; she just _needs._

There’s a faint, metallic noise as Kuro undoes her belt. “Are you going to beg for me this time, like a good girl?”

“Alpha,” Kira pants, stumbling over the words of their ritual. She turns her head, already breathing hard as she stares sightlessly at the wall. The closet door and the tell-tale dark gap haven’t moved. Kuro always wants Kira at her dirtiest, her most submissive and animalistic - but maybe it’s not just Kuro who wants her now. Her body throbs with heat, pulses that whiteout her thoughts so thoroughly she can’t remember what she was so worried about only moments ago. Honestly, right now she wouldn’t give a shit which one of them was between her legs as long as there was a knot ready for her. “Alpha, please, I need it…”

Kuro’s shaft pushes between Kira’s thighs, a familiar sensation: wide and uncut, the knotted base already starting to swell with interest. Kira’s pussy gushes, thighs shaking at the slow slide against her folds. “Nnngh!”

“ _Beg_ me.”

Behind the crack of the closet door something shifts slightly, just enough to disturb the shadows.

“Please,” Kira groans - a sound she makes for nobody else, ever. “Please, Alpha, fuck me - “

A hand comes down sharply on the side of her ass.

“ - I’m yours, I’m your slut, please, _please_ \- !”

Kuro pulls back, aligns herself, then slides home in one smooth, hard thrust, painless for how soaking wet Kira is but god, so _much_. Kira howls, and the hard bulge of Kuro’s knot shoves against her hole. “That’s right,” Kuro says. “ _Mine_.”

Breathless, Kira’s eyes well up with tears of exhilaration, and she stares ahead at nothing, at the movement in the dark Kuro doesn’t even see. “Y-Yours.”

**Author's Note:**

> Keith/Kira in this story is the step-sister of Shiro and Kuro, who are twins. Kira and Kuro are hooking up, but Shiro and Kira have unresolved sexual tension and almost act on it. Shiro watches Kuro and Kira have sex without Kuro's knowledge.
> 
> Feel free to visit me on [the other blue hellsite](https://twitter.com/mistlethace).


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